import java.util.Stack;

public class testwork2 {
    public boolean isValid(String s) {
        Stack<Character> stack=new Stack<>();
        for (int i = 0; i <s.length() ; i++) {
            char ch = s.charAt(i);
            if (ch == '(' || ch == '{' || ch == '[') {
                stack.push(ch);

            } else {
                if (stack.isEmpty()) {
                    return false;
                }
                char ret = stack.peek();
                if (ch == ')' && ret == '(' ||
                        ch == '}' && ret == '{' ||
                        ch == ']' && ret == ']') {
                    stack.pop();
                } else {
                    return false;
                }
            }
        }

        if(!stack.isEmpty()){
            return false;
        }
        return true;

    }

}
